Isn't it better to have more powerful single thread performance for developing in single threaded languages? Looks like a step backwards than? Double the core count and more l3 cache sounds good, even though they crippled the base clock speed.
In practice, the clock is set to limit power usage and thermal load. A better-cooled system will automatically run faster (not really applicable to laptops), and if you're only using a single thread then you'll see the same clock rate you did before, or a bit above.
"Our stress test with the tools Prime95 and FurMark (at least one hour) on mains is not a big challenge for the ThinkPad T470. Thanks to the increased TDP limit, both components can maintain their maximum respective clocks over the course of the review. [...] The two CPU cores maintain the full Turbo Boost at 3.1 GHz and the graphics card 998 MHz."